fix: define type of build

Purpose

Make sure that -DNDEBUG is defined.

What it solved

If type of build is not defined, CMake enable optimization but do not define -DNDEBUG as it does in Release or ReleaseWithDebug.

The library heavily rely on -DNDEBUG and enable some feature designed only for debug such as deadlock detector. This feature must track each lock operation to determine order of locking which have significant impact on performance. What more it can abort application.

See https://abseil.io/docs/cpp/guides/synchronization#deadlock-detection

Deadlock Detection

... Note that deadlock detection introduces significant overhead; it should not be enabled in production binaries.

It related to these issues, which is Linux specific:

• https://github.com/grpc/grpc/issues/39461
• https://github.com/grpc/grpc/issues/40390

Diffrecies

CMAKE_BUILD_TYPE=NONE

[ 26%] Building CXX object absl/synchronization/CMakeFiles/synchronization.dir/mutex.cc.o
cd /workspace/salsa/abseil/static/absl/synchronization && /usr/bin/c++  -I/workspace/salsa/abseil -g -O2 -ffile-prefix-map=/workspace/salsa/abseil=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wdate-time -D_FORTIFY_SOURCE=2 -std=gnu++17 -Wall -Wextra -Wcast-qual -Wconversion-null -Wformat-security -Wmissing-declarations -Wnon-virtual-dtor -Woverlength-strings -Wpointer-arith -Wundef -Wunused-local-typedefs -Wunused-result -Wvarargs -Wvla -Wwrite-strings -DNOMINMAX -MD -MT absl/synchronization/CMakeFiles/synchronization.dir/mutex.cc.o -MF CMakeFiles/synchronization.dir/mutex.cc.o.d -o CMakeFiles/synchronization.dir/mutex.cc.o -c /workspace/salsa/abseil/absl/synchronization/mutex.cc

vs CMAKE_BUILD_TYPE=RELWITHDEBINFO (-g and -O2 as in NONE)

[ 26%] Building CXX object absl/synchronization/CMakeFiles/synchronization.dir/mutex.cc.o
cd /workspace/salsa/abseil/static/absl/synchronization && /usr/bin/c++  -I/workspace/salsa/abseil -g -O2 -ffile-prefix-map=/workspace/salsa/abseil=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wdate-time -D_FORTIFY_SOURCE=2 -O2 -g -DNDEBUG -std=gnu++17 -Wall -Wextra -Wcast-qual -Wconversion-null -Wformat-security -Wmissing-declarations -Wnon-virtual-dtor -Woverlength-strings -Wpointer-arith -Wundef -Wunused-local-typedefs -Wunused-result -Wvarargs -Wvla -Wwrite-strings -DNOMINMAX -MD -MT absl/synchronization/CMakeFiles/synchronization.dir/mutex.cc.o -MF CMakeFiles/synchronization.dir/mutex.cc.o.d -o CMakeFiles/synchronization.dir/mutex.cc.o -c /workspace/salsa/abseil/absl/synchronization/mutex.cc

and package

--- libabsl-dev.txt	2025-10-03 19:09:04.510651934 +0200
+++ libabsl-dev2.txt	2025-10-03 20:02:07.094765229 +0200
@@ -369,22 +410,30 @@
 /usr/lib/x86_64-linux-gnu/cmake/absl/abslConfig.cmake
 /usr/lib/x86_64-linux-gnu/cmake/absl/abslConfigVersion.cmake
-/usr/lib/x86_64-linux-gnu/cmake/absl/abslTargets-none.cmake
+/usr/lib/x86_64-linux-gnu/cmake/absl/abslTargets-relwithdebinfo.cmake
 /usr/lib/x86_64-linux-gnu/cmake/absl/abslTargets.cmake
 /usr/lib/x86_64-linux-gnu/libabsl_atomic_hook_test_helper.a
 /usr/lib/x86_64-linux-gnu/libabsl_bad_any_cast_impl.a
@@ -808,7 +858,12 @@
 /usr/lib/x86_64-linux-gnu/pkgconfig/absl_variant.pc
 /usr/lib/x86_64-linux-gnu/pkgconfig/absl_vlog_config_internal.pc
 /usr/lib/x86_64-linux-gnu/pkgconfig/absl_vlog_is_on.pc

alternative we can only define -DNDEBUG.

@bbaren